The airquality dataset contains daily air quality measurements in New York from May to September, 1973.

We are interested in the relationship of the following variables according to different months:

• Ozone: Mean ozone in parts per billion from 13:00 to 15:00 hours at Roosevelt Island,

• Solar.R: Solar radiation in Langleys in the frequency band 4000–7700 Angstroms from 08:00 to 12:00 hours at Central Park,

• Temp: Maximum daily temperature in degrees Fahrenheit at La Guardia Airport.

##    Ozone Solar.R Wind Temp Month Day
## 1     41     190  7.4   67   May   1
## 2     36     118  8.0   72   May   2
## 3     12     149 12.6   74   May   3
## 4     18     313 11.5   62   May   4
## 5     NA      NA 14.3   56   May   5
## 6     28      NA 14.9   66   May   6
## 7     23     299  8.6   65   May   7
## 8     19      99 13.8   59   May   8
## 9      8      19 20.1   61   May   9
## 10    NA     194  8.6   69   May  10
## 11     7      NA  6.9   74   May  11
## 12    16     256  9.7   69   May  12
## 13    11     290  9.2   66   May  13
## 14    14     274 10.9   68   May  14
## 15    18      65 13.2   58   May  15